PAR7TAT.I..TIT r By
R. L. Parshall,
United states ,Jepartment of 4;ricu1ture, Bureau of Ylgricultural ngineerinr-,
S. F. cCrory,
THE PARS7ALL 1!-ASURITTG FLUME By
R. L. Parshall,
oenior Irrigation _i-mgineer.
Prepared under the Irection of . .
Thief,'ivision of irrirf,ation, - 311reau of igricul-tural hngineering, United states Department of
Agriculture.
Based on data gathered under cooperative aFreement between the ii:ureau of -igricultural EngineerinF, U. 3. Department of Agriculture and t),..e .;olorao
Agri-cultural Experiaient Jtat ion. Fort Gollins, i3olorado.
T. PARSHALL 7EASURIr0
-LunF(1)
By ,aiph T. Pars11831:Tater is the most valuable asset of ' stern agricu]turc. :flr7e expenditures have been mde in tL. developmert of
1rri! 1O. ,i(pr:s am; canni sytems to furnish tater to ftirms. Those it V: cost of preparing large arevs of lands for irri aioL and the estab]islment of legal rights to the use
or water, represent a vast 1rriaion investment. The extl.sive o'itlnys dread;! Eide and thse v,hich must be faced ir the future emphaize th greet reed for t e cons rvetion of irrintion supnlies, and in this relstioi-, correct measurements
or
flov: scY)1.:1 *e the bnsis of any plan of svin,c7).(1) This bufl-Ain is a revision o' 'olor :J.Tict]ture]
:neiinert ,tation Bufletin 336 entitled "The improved ':crit iri -rrchj 19P.
In ninny cases, the EO:sence f italle iee s for ,:ensurir' flovinyter an in,icatior of irs iffereT.ce or. 'he
part of the users - o much6' a isclosire of their lac'z of knowledge of such Jo-vices '.'ea,'trement may be accol-i lished
by vario methods mon. Jr les6 sui 4 e6 tc, conditions, siich as grade of com.3 or ditch, quantity of yftter, or interfc'r-once with flo. by sand and silt.
. he right to use water for tion is decreed by tLc courts whicl., provide that definite amuur, s !,,Ely be div,:rte from natural
wLter course;. meas.rerLent, the appropttor Of w%tcr ce not make a definite
-2.
statement as to hov. va -tor be actua]ly uses, ani, if a dispute sho arise it )e.l. e for hi to furnish satisfactor:: ,r,roor of his establisi.eu ri:hts.
1.r. some of t - e esterL :3tates, Leccuse of the scarcity of water, it is of prJ:..e IL ortarce t.-,at its easure'bent te
ac:: rate. her legal questions over Thater rigits are infolv-ed, con. iderable advt-tage is to be gaine by havin'
definVe records
or
mess :remel t 7.ade b- 1s:no prcticr2 device of recoa.nized acclracy.
Someties because of fa,Ilt: -ieasur' ments, 'h farrler's water supply 1.3 so restricted to interfere weri0u5ly with the -laturin of his crops. ere dependable mess .re. eilts niade, he irerefise in va -lue of the crops oul-: more than pay for th:e expense of insta linr3 aiptainir,- a good, reliable, measurin,- evice.
It woul' be exT-ected 51117e
any lar'e . larqfacturing or co:mercia 2,0444-L.kw44.0 t 11 ramifications, would -easure all rater deliv7ries tt at least0. exactnes, , any of the!, stir estimate
deliveries or use fatilty methoCs of neasureraent. ihe principal asset of' sue. irrication enterprises is v.ater, and their principal dut” is Vie proper an economic distri-bution of t' e sq'ply. Fairness to the wwtor users and
successful business nanarement botl, de! and tbmt rAiable measurements be made a3 a basis for all water transactions.
It is generall. believed ttat the, eaoure%e: t of water is an in'ricate procese, but ac,lirate eas:renents cr. reF.'ily
-3-proper settin - or dimensions of the device. he water user himself, i,ith li!tle practice, should be able to ;1 asure the water delivered to hi' with a satisfactory ,ierree of accuracy.
The easurement of water florin- in open car. els is a mrtter o iri-ort-nee u-hout the irriFrated areas. he cost of the -easurin struct,ires is complained of in many
instances, a - Tell as 4,11 fact that the particular installation ma i not be Ihell s-ited to ;he con itions under which it Lust o-lerate. .:,ccumu]ations of debris ir :any devies have
rendered tJic.,,,asurements either questionable or obviously of no va3ue, and 313ch failnrcs havc,in somf_ cases, discouraged the use of irove 'ethos better suited to the conditions.
In the easurement of water in °rer channels, the teir ha bee, o!Y generally used for small-to-mo,ierat, rims. LaboratJr tests inciicate that At is the lost accurate
practical .:tea.v.,: for rteasurin 114ater under favorable con,tions )
but if the pool o‘channel section ira ediately upstr am
from eir crest accumulates sediment, the required vertical depth of water below the crest is correspondingly reduced,
thus interferinc, with the acculac of 1;1-Of:, method of measure-ment.
..here
the
grade f the c'-annel is not sufficient to Permit the use of standrd yeirs, orifices have bee. used vithvaryin - success. 'creriments see .. to in;icate that the constants hi 11 apply tc thc- true ;11 clar!,es are affected b t. e share of t c orif'ce as yell az' certain cowraction s v.h :c a en a: no' be correct, 'hus rendering the practical vaThe of this de,Ace rater uncertain.
-4-Ho ever, its property of in iectirJ. the dischare vith a relatively small loss in hen is an adventa7e.
The of the °vices most COrimOniy used to , easure
flows is the rating flume, 1%hich is a siïc:1e structure built in the cannel .1!ere the floor i level, sot to t17, rrade line, arca vith Lts side wal2s ei'her vertica) or inalined. This flume 1.= cn311.:rrteu by current meter e.easureric,nts, or by other meurs, ..hc.re the rate of dischare varies with the uepth of the stream, which is in,icated b. a staff gae set on the inside face of the flume. he ordinary rating
flume is not altogether reliable. Often a deposit riccumu3ates on tie floor of the structlrc, thus cuttin down the cross
section of th. water prism, which, in turn, aCfects th veloc ty. Flow condition dmrstrea- froF, the rating flume 28:• c ange,
staff
causing ttiel,gare rendin .s to be affected to such an extent that the indicated dischar.es *11_ be considerably in error.
rrass, weeds or willows in the water 1%113 affect
the rate of fic . , ?:hich causes error in the disc,'prge readinf7s. On the other hand, a smaller loss of head will suffice for
measurements by en's of the rain' flame than for any other practical device, an fo, 'his reason i is ver:- commonly used.
7,arly in 1915, tests were conlu,ted at the fort "L'ollins hydraulic laboratory of tie ..%)lorauo A,-ricultural
station on a eater-measuring device having a convergiw' inlet, straight throat section, and a diverging outlet, with a level floor Ilreuhout. These tests were mede to determine the most pr(ictica] n,-les of convergence and
.5.
diveiTence with relation to contrceted section, as vell a3 the practical length of the structure. :he wells of some of the tested structures mire vertical; in others they inclined o.ltward fro, 21e axis. ...liter certain conclusions busringupoL the laost practical dtJie:,sions to
be usede a series of call:rations was nade on flunes of various widths and of both those tyl)es. The first tests were :ade by V. !.!.. Cone and were reported by hin in the Journal of
Agriclltural -eseerch, Vol. IX, No. 4, p. 115, April, 1917.
Pecause of the tany apparent practical a. ventsp,es of thf: Oevice, more extensive investirstions iAsr, made at the hyJraulic
laboratory,
Cornell
University, Ithaca,r.
Y., where lerre novo were avellable.(24se a
8, 0 0 ,r w 00 onn o s.,,rvations, werereported in Pul. 265 of thc Colo. 'JPricaturtil -xp. 3tation t entitled "The Venturi Flume".
The wtiter-measuring de- Ace h rein ,escribed, calle 7arshall measurine flume,(1)is believed to poasess the
characteristics which will ake it meet general field conditions more succesfull than its predecessor, t'Ai Venturi flume, as well as obviate many of the objections to the ueir,
orifice, rating flume or oher measuring devices
now in.general use. This ,.els!tring, !Alma is intended prilnrily to meet r!,eneral field conditions where extroo accuracy in the '46§iifiiI.10011t is not required.
Oa This neasurin Ievice 'been naned t1J) 7,nrAt111
.leasurinr. flume at the surr,pestion of th , , lrrition Committee of the American ociety of Altil 7nr7in - ers with tl7e
approval
.6-Department of Agriculture aLd the lorado :,gricultural isxj)eriacnt ‘Jtation.
It is -,ssumed that the deviation betveen the actual and indicateS discharge will be within 2 to 5 percent when the flume is operating under normal conditions.
Experience in the field, as well El.. laboratory tests with ol t 1- of Venturi flume, s e to in,,:icnte tlf.t in order to operate the device successfully it is desirable that two depths, ma and HI), be observed simultaneously at the proper points on both si',-tes of the structure, and the nean values referred to a faischarge diagram to determine the rate of flow. Tests anO field observations on the new uevice sow
ihat, for free flow, the ,]ischarge ma:: be deternined by a sincjle reading. For the determination of submerged flow, two f7age readin7s are recessary, two of the four Ft-Ives forlerl: required bein eliminated. This re ort prec'ents
the ,lischer-e ,lata in tabular form, which is believed to be rAore convenient than that giveL former re.florts Or the
venturi flume.
The Parshall 4;; 1'flume differs in design from tLe
cld type in the reduction of the convergence angla from 18° 26 1 tI 110 19 for its unstream or inlet section, a lengthenina ef the throat section from 1 foot to feet, reduction of the
'iver'-,ce angle of the lower or outlet section from 185 26' to 90 28', and the placing of a depresion in the fl3or at
the tilloat sectior. The lengt'rl of tne si6e wall of
convergin section (in feet) is also change,. in accordance (4)
wit tly) arbitrary rule
Figure I... The Parshall measuring flume with well provid.
TABLE I.—STANDARD DIMINSION5 AK CAPACITIES 0 (Letters rqfor to rigurs
-etiii PARSULL MKASURING YLUVE
Crest Dismosions isA and inches iree-flow Ja„.801t,i
gax i men M LIU. 42
Lomita Head Head
A
2/ai,
3 2/3B 0 Ha Lisch. Ha ;isoh.
iset r eta :AC.
-rest 300.-L. O L lb.1 0.::.0 O.& 2 b' 0" 3'4" 4' 10 7/6" 3' 3 1/4" 3 3' 11 1/4" 2.b0 3e,.1 0.40 0.66 b' 41/6" 4 1..' b.0 .4 0 20 0.97 4 6' 0" 4' 0" b' lo b/8" 3' 11 1/8" 5 6' 4 1/1" 4.b0 67.1 0.20 1.26 15 6' 6" 6' 4 1/2" 4' 3- 6 7' 6 b 2.Lb.60 8 0 2b. 2.22 6 7' 0" fr'
ty,
6' 10 3/8" 4' 6 Ve 7 u' V" 2 0.L 103.t 0.2b 2.63 0" 7' 4 1/4" 4' ik.) 7/8" 8 9' 11 3/8"b0 141. 4 O 30. 4. 08 10 1/6"Ili 1 3/4" 0 133.b 0.30 4.62he general dimension 0° flume ns shown in fir. 1 refer to the tabllar dimension;. given in table I.
The length of t1J.; convergini7 side of the strIcture ie
discssed more fully in another section of this bulletin.
The lorwth c) the diverrin section has beer tnken 65 3 feet
for n11 nt the throat section from 1 to f-et
inc7usive.(40 In the -old flume the floor level
throwihout, Alcreas ln improved type the floor in the
throu section slopes dovmard at a rate of 9 inches vertioally
to PA, inches horizontally. At the. poin ,Ilere the diverging
section begins, the floor alopes upvnrd at a rete of 6 inches vertically to 36 inches horizontally. The floor at the
loer end of the flume is 3 inches belot the floor level of
the upper or converrin.' section. "he 3-, 8- and 9..inch
flumos)discussed elsawhere,tire of special. dosixn.
Hydraulic Laboratories.
Two laboratories ere used in ;:eir lopin,- this flume.
At one, tIccArat:r and precise work is possible; the other is a
ficl laborator ofA cepoeity such /16 to perlit tIls study of '
flow through structres of large size, an.:1 whom the accuracy in mcasuremont of flov is well 7,ithin practical limits.
The Fort 'Collins leborstry (5) has a crin!leity of aboktt 18
3econo-feet, vhere c_iscflarge is •A.4„.3u):ed volumtrionlly.
(5)
W.001101. ..4.4•11.11
or mor complcite descriplion, see 4 t '01.310 V01.7C,
n.G02, October, 1913.
•••••••
-8-supply reservoir vh2ch has a capncity of three-fourths of an acre-foot. The wf .t.,r is leJ fro this resrvoir by
means of a channel, into the la -oratory, .here the experiment-al structures are tested. There it is possible to naintain a specific depth or discharge lJn enouF: to deterrline quite closely the condition of flow. It has bcfr foun, possible to make calibrations come within al-out 0.005 second-foot of the ,4,ircarpes determined volumetricly.
The volumetric tanks are of reinforced concrete th -etir% , •
cepncit;, ts--/a,--roxi-1,+ely that of the supply reservoir. The Amount of water added to t ese tanks or bf,sins for any
particular test is Jeterulned by hookp.,age readirgstc a limit of 0.001 foot. An electrically-driven centrifAa2 p-m7 ret•rrs the water to the supply reservoir for ;se a:7ain. The calibration. of thc, smaller flumes uere made at th_s labmtor,, where t , e discharges were ,,leas,:,red to thousandths of.second-feet, and the denths or heads
affecting the discharge throuh the flumes were determined h-..okgage readings. These exr;erimental structures were built of wood or sheet metcl, accurate in dimension aLd of
•
sufficient depth to cover a range of discharge such as woulJ be found ir actual field pr&ctice.
The field laboratory at Be lv e (figure 2) is 6 nlles cast of Fort Collin':; at the headworks of the 7ackson hitch, on
the Cache la Poudre T'iver. It consists of a reinforced concrete cannel 144 feet wide and fee deep, with a preseLt
over-all length of abo.it 150 feet. At the lower end of this channel is a weir box 25 feet wide 10 feet deep, having in the
.g-At this laborttory, in 1923, whe the calibratior made the 1r,rger sies of the Prrshel 1 E17,71rinc, flume, the
concrete weir boy was of the same vAdth as be channel end had a depth of 7?- feet for a distance of 24 feet. the end
wall of this weir box wts a 10-foot sndard rectan - uler weir, patterneC -fter t!.:c 10-foo weir celibrc,te by J. P. 7rancis In thc early '50s at lowell, Mess. Pecause these weirs were of similar diersiom-,, the diec)7arr7e cur e for the weir used
based upon results of Francis' experiments. he Tt&rer measurinv flumes were Lull in this concrete- channel at a poin 1L'strevm weir box. he water vies admitted to th cllinLel et its up or or, thence flowed through the
expert:dental structures, and finally carefulz: neasured over tel standard Hookgages wee mounted on the nociel
structures a such points as permitted careful measurenent of the u-7.1r head, Ha, and te throat heed, 7!b* he head on the standard weir.was determined by ens of two hookgage readin,Ts or opros'te reir box (fiF;ure 30). All hookcage read1n7s :ere observed to a limit of eccuracy of 0.001 foot. Downstream fron the expethental flumes an adjustable baffle provided which permitted the regulation of the cess,..7.ree of submergence* At this laboratory, calI'-:rqtions were made for flows rengin7 from 5 to 90 seco. d -feet.
Action of the -Jarshell reauring Flume.
The fundamental iae& dictatirr tbe dest7n of the flre Is beed u i the effect of the incre-, sing vel,,city in the convergin section, resultin from the oonstantly decreasirc cross-section of the ater prism. A:) the flowing stream
.441111111116.
P1/7mb° be— Ex- erimontel t..foot Parean neestirinr flumc*
reaches the the crcst, which is ihe junction of tle upei level floor an4 throat floor, it hhs virtdally attained Its maximum velocity. For the free-flow conaitio , te strewl 1,, carried down ,he inclined flo r of the throat
an,, with the momentum thus acquired, is carried upyarl over the inclined floor of the A.verg!inc. section to tl . exit 1-..(1 of the structure. -ecausc there is no obstruction to the flow as just described, this condition is ca led free flow, as silo n in figures 3, 1?,, 21,26 and 27. :her the re'istance to the riming water in the chawlel dornstream from the flune is gre. enourt, the momentum through the thrat section is not sufficient to prr-it
clearir-smoothly in the iiverginF, section. thu.-; rostrictf7
the flow, the water surface is raise .1 in 4- h- e -vt t e flume. In this transition o' flol l the phenomenon occurs
known as the "hydraulic jump". "ecause of the dol,,nward inclined floor the thrcat 3ect1on, this jump is
produced at soi:.e ctistarce Llo,Lstrelm from the crest, anu is, in effect, the means of warding off or holdin bac
resistinf7 water in the diverging section. In the
foration of the hydraulic jump, a portion of the velocity hen in the strec-1 pesin the crest is converted into static head, which cnuses th str' m to flat at a slower velocity but greater dertj- beyond e point where te jump is for:led. As the rnsisttfnce to th flow In *J.1.2 diverging section i - further increvoei, the jump ic reduced in its efectiveness and at the s-lae time crowded back in'o the throa section. As the jump ;.ipves upsTrea,' into the throat
section, n (:ordition of downsres- depth is reached where the momeLtun or push of the water over the crest is re(Aueel by -the resiStance to -the point of decreasing -the dischare. This point is called the limiting derth -r critical degree of sulytiergeLce and is importaLt bnonuse it defines the unit of free-flow discharpe. The amount of waer florirw will be mdiminishe:; until the eiter wIrface at the loer or dotnstrea•. edge of the throat has bc'n rn.I.se to such a point that the depth here, or !lb, it; approximatel:, 0.7 011 of that in thu converging section at the gage poirf, 411, where both these depths arc l'eferrod to thv orcst eievntiol, as the datin% 'Alen the r Astance to the flov doi:Jistrean from the structure is furtLor ilicroutsed, because of laclz of .71.1Ade or or oheckinp of tha flow by ienns of flashboards, or other-wise raising t113 water Evirrace beyond this limiting derth, a reduction in the discharge resIts. This cond - tIon is celled submerged flow,
-rhis limit is applicable for flunes of 1..foot ridths or i-rePter. 7or flure of smoll size see discussion -age
In this disc sion ho deree of submergence i thu rn+Jo of the thrcJ1A r , w to unper pnge,Ha5expresoed PS a decimal fraotion.
In the plan n eleve!ioi th, Pershall T,easuring
flume (f17ure 13), tl,o lower voftt r s. xfce, (1, in the downs. stream section ::;hoYs tLo comlition of frAa flow, whilo the
upper surface, P, indicate approximato elevation of tt'. fre-f"low disoherge limit. The elnvetion of this surface at any point betweez, is within the free 10 zone,
arid the the disc1iare for this range is (1 funct on of the flume's .idth or size am, of he ur r hn i,"a, - hich
Is measured at the t;o-thirds poin' aJon the corveri7in;, side of the structure.
Characteristics of the Flume.--he ::ru.ctic6.1 use of 1—, :'arsh11 c has de.qons rated thr.t it possesses
many desirable c',Iracteristics tic, is not subject to rian: of the •lissdvantages of other devices. It may be operated either as a free-flow, sinc,le-hend device, or under subnerRed ,flow conditions where to heeds are involved. ecause of the gontracted section fit the throat, the velocity of water
flovin - struct';re 13 rr,an'vely P,ref.ter tan the naturP1 flov " stream, arid. for t'ls reason an. sand or silt in susvensicn or rolled alonr tJ'e tto of the channel
carried through, leRvin', the flu-le free enosit. Velocity o' approach, which ofte l'ecomes a serios f'ictor in t'-e or ration of weirs, h's liftle or no efect upon the rate c) .dscharqe of '11e. (See -liscussion
-It is accJrnte en.uh for s21 -11-7oses and since It re/1 Inc clenr of se iqeLt M re'7, bility of its ea. re merit is believeJ. to be !,ret.ter t (.t L/f oL, er metllods.
• Usually, condition: founc in the field will periait it to ope ate with a free-flov, disc'r.arre, thict is a f_ir:cti.:)n only of a sin,.71e 7,1tb a Aeir. rho loss of head for the frce-flo-. 11oi is foil!!., to be at. ,ut 21- percent of that for the slc-d. rl ovrr-our weir. 'Ti-ere no
way tr• alter tovc or c use R 7c7c in he flume, moclify the er:-Lc2 above or , eloT ot',erIise
interfere the original condons for the pqrpose of inerasirr- '1114 dischare to effect a wilfully unfair measure-ment,
The design aml of tIlis dev,ce lave shpur, that it
is capable of withstandit- high degree of evlbmergence
before the rate cf discharge is r:!duced. T3ecause
or
tl,lsfact it will operate succensfully whet**, tl7c overpour witir
fnlols because of th.::7; flat grade of W-a!nel. A ride
rnnge of cornett:- of --Amsurement Ills boon provided in its calibration, an it is, therefore, adrptA to lise on the snail ferl-1 lateral no 1%(131 as c`lIrrels of ler-- capacit .(1)
.-...--(71 olo, Agri.
3'ation
.
L1W.., "Parshall ,iumea ofa .:17e , 1932, discusses flumes of larger oize,
throat width of 50 feet and havi. a cabcity uf 3000
second-feet.
The structure
itself may
be builtA either wood or concrete,or, for the smaller flumes, of sheet metal. The fact t'lit
the
design
specifics certain anr,les does not grwitlyI'bII the wer7-
or
building, since all slutfaces arcplat,e; hence the material
may be
readily cut to fit properly.The practical 07eration of the flume is tm-ple, and any observer can make the recessary rendings and apply them to the table
ankl diagrams to determine the discftarge. rtere the flor throu h thn flume is submcrgeJ, nnd two !ends or depths are
observed, a rale recordin,7 irstr' a Ised Alich
indicates on a c of tte tTl; fiends (Bee
figure 28). Theverocorded data, rcforre: to the si,e of the rlilme lewe sufficient to determine th , flov over any
-.14-nr)rio: of time.
Consti-tctio o" 77-e L-lental rind Method of Ctservation
The experimental f)ume at both 7art ;ollins and
Bellvue laboratories ,Aere ordinar:y sill3 arc, posts tere 2 by inch pieces, Lhile the floor ar— vulls wore made of 1-inch boards, surfaced on both si.ie. In The building of the.;e strict,Arcs particular care was taken to have all dimensions exact. _hen the si e walls aLu floor bechme wet they seelled, an,-, due allov.ance vas made in havinc the throat width Os size of flume slightly greater than the nominal length in or or t :t, wher the structure was completely soaked, the sell1r v.ouiu Lring. the
di-lersion elose to the true value. Tlinensions of the structure er c - cckod occasionally 'o see whetb-r or not
bey re:qine,, within practice.? hits.
The stiliin well3 wer metal cans, about 10 inces in diane*er fro..2, ;!_ to 6 feet deep. he deer cans nere
•
used at the ellv e laboratory ES a matter of convenience. In th( m_untin? of hookgages, care in ta7er to hEve them securely fixed. ;).t the 7,ellvue ]aboratory, a 2 by 6-.Inch plan hs set vertically and rigidly fixed to insure a -fArst arrur in depth m.asure%'.nts. The metal stilling well tLS placed against the face tie plank, resting, firr41
upon a solid base. I /4-inch pipe co_IL.:,ction W6S provided at , bottom of tell, an,: from tiis as led a piece of co mon .rde. 'close of t''e S C A.ameter, connecting to the wall of the 1..zie by similar pl'e co ction a
-35-experimental flume was a 22 by 22-irch metal pate, pieced in a framework consietinfz. of a sot of flashboarde. This gete end the flerhboards rede it possible to secure various degrees of subleLergence and to regulate the flow throu,7h the test structure. Deifies were placed upstree from the exeerimental flume as well n3 dmnstream belor the submergence bulkhead.
Each morning before operatione era beFun, all hookege ooris tents eerf, determined by means of an engine r's level and rod. The mean elevation of the crest of the test
flume was accurately determined by several observations at different points. A lirht wooden rod -with slidine, target eee placed at a point of mce.n elevation an the target set exactly at the lire of sight of the instrument. This rod was then placed upon the v, rious hooks of the gages and the gages vere adjusted so that the target again agreed with tile line of 1-it o.r the levelinr instrument. The hookgrge rel dings ther. -eve the constant correction for each -age. This same method was employed to detereine the hookgage constants for the stendard rectenguler weirs.
'ater was admitted to te concrete chaenel by man:: of the !lain reeulatine gate an::. after the floe had essumed a constan' .eon .Atioe observetions we e taker as fol. os: An ol-eserver r;tirted by reading the upper head, or 7a, on the flume, thin observation to a note-keeper who
recor6ed it on a spealal form, and then read in proper ardor all other ooke7ages, calling the readings as the eere observe. For the most part, five 1001:FirOF ere observed, three cx tte experimental flume and 1• o on the standard eir, e coelete
rou.r... of rerAings usutlly re 'ulrA el,oiit one nr: one-Ynlf ninute, rind rherei the variation in the .'ter Emrface
.vre small, five comlete sets 3i.e assund to i.e sf"icqent to c;ive the cor ect rar, ot Er.io, :lore obse vatjonn -(17
taken.
In the old ty-e of Venturi flume it was found thl: te dorrstream flo condition ere sue: e to sw1r17, the cJrrent from one side to the other, ap-arontly without cause. '.1118 sirinr was found to affect t,e rendinr! of head in the
oonvergini7 section. '7o deternine whether or not h,.ads observed on either side or the conv rginc sectior of t. arsa11
mensurinr f3ume were t.c seme, approximrAel: 200 observetiors were nsde 17 b7! havin tro hookgege connections, one on eacb side at tn proper pcirt. These obsevtiors shor
thnt the lif"e ,,.cce in the t-o readings wns very
and it ca, therefore, b cerely assued thst the u per he Ha, may be observed on either side vAth o.;ual acc:acy.
At the Be21vue laboratory, the loss of heF.I.J hroll...7h the flume was detemined by staff ges read dirct, te zero of the
gages being set at the elevation of the floor of the conv-rF-inr section. These ga 1:ere so sitdated tht the elevation of the wt:ter abov and belot ti-le flume coulci. be determined
quite acciJrately. At the 2ort Collins laboratory, vher calibrations :er riAe on the smaller-sized flumes of small dischare, th. loss of L,Thd vas deter dried by mean of huok-gage reti.di.
Free Flo. Formula
Tho delta uror whie the free now formula is bnsed
1 ,1
!leads, fla, for 159 toto, th Ce:ree of slAber6cr'ce is les 70 percent, thee tests bei divid according
o 2ize flnne ns forovs: 1-foot 'flume, 27 tests; 2-fuot flume, 28 tests; 3-foot flume, 34 tests; 4-foot flume, 21 tests; 0-foot flume, 20 tests, and t.1- 2 e-foot flume, 29 tests. The datc obtained from the tests, 'en
plotted to a loi7arithmic scple for the v!-.rious discharges cor.res . ondinc heads, shoved ver:- ri'nriy a strait7ht-line veriation for the variou.; rizes of flunes tested. Upon edjustin - t straiht line to tese irdivdual scts of
plottincs, it va:; oserve':! t:1:;crirge intercepts for the upper hee., Fa, at one foot are ver7 closcly proTortional .to 0tinies the , dtl- of the flume in feet. The elope of
the lines for the various sizes of flume is not the stuRe t
thus showin that the values of Vie exponent of the upper heaI, 7. 1, are not idertical and therefore vary with ths width or size of flul;o. careful inspection of the pIoted data, values of the Intercept awl 3lope have boe. determined for each size of flume, as given in table II.
-18-Table TI.--Values or Intercept 3 and 31ppe n, Lo' }lot for Law of *';:e riov: .:Ischnre Through Different-sized Parshell mersurin- flumes
Coefficient 0' Exponent n of Ha
A.ze of
—1-17WFFepf lomputed Diff- nm-uted Lo -lot lot Value 4. el-mee Sealed Va3ue Value or
erence Teet 1 3.98 4.00 2 8.00 i).00 3 11.96 12.00 4 16.02 16.00 6 2,.05 2*.00 8 32.00 32.00 Log riot 1.522,C.026 f0.02 1.527 1.522 -0.005 .00 1.52 1.550 - .002 + .04 1.55 1.536 i .0:1 - .02 1.574 1.57T 4 .004 - .05 1.592 1.5:-,5 4 .003 .00 1.608 1.306 - .00? 0111.11•01•111•10111111..
The furLumentel la f;o . 'he free flo;. dizchE:rce tiki-ot01 the •4A-urin flume is:
J I'
where "._uv.ntity in second-feet
loefficient thich is a function of the size of the flume.
Ha=Te u.7Ter heed in foot observed at u point distant ustreixi frorA the crest two-thirds the len!qh of the 3onverg1n17 section
n = 7xponent of the heul 7a
'y inspection of tbe data in taLle II, it is evide t tint, as an approximatior, J =, 4W, where W is the r;ize of flume or width of throat, in feet. The relation. of ti-n ;lope n, end
0. ,i.dth of flume has been este lished as n 026 Hence, the complete forilln Tlay be stted as
0.26 ,.,. 1.522W
,
The form of ex ..resion enployinF, th doui2e ex7onent of Ka may nt fIrst aHp(: - to be cbrvlIc80:1 end unus-Jal. Imever s when the simpl: o7ortitLn L Jror7led to reduce to tle;
proper val':,e of the 5); 0. c.:1.t for therlcrtc-tic;r of
26 24 0 22 lii Li-• 20 0 CD 16 Z 14 0 IL • 10 0 I- 8 o Lii Lii 2 0 7 6 5 4 3 2A NEGATIVE
9
•••••., I 0 I 2 3 4 5 6 PER CENT DEVIATION7 8 9 10 11
POSITIVE
Figure 4.--i,lom11arieen in perooLtace of comp. puted to observed free flow discharge through experimental flumes.
-1I—
no more difficulty in its solutin than the simple a:inch7 -e, .formula for a 'ceil:• or slay.:Icrged orifice. This
c.,quation, Siirl id the product form, is r adily olved by ans of loarithms.
FiEurc 4 shows graphicalL the Ereement of the com uted discharpe, as determined by the free flow for 71, o
obev,rved. te base. This comnrisom eludes, in addiA.on to t?In 150 origina2 tests mode in 192:7, the 130 check t(74ts nnee I:, 1928. -Ile dat upon which this diagr4l4 is beed ver, levelepe by ex- rel7sing devintion betveen
4.54
arC c=puted disennr4e 4c rrIrcent ,here the uoLi-utcd vtAr.; f;4r(p7:ter tir‘e obsnrvc:
nore0070 nositivn, nni 1 1.1c
tS e observed disOnr: the percenta:7c 747as nrzative.'
tabuLition wns ten ' v47qcs, zercl
devor inclqded 41.1 values bet.9on -C.4 ar:! 40.5 Iplve; 1 percent posve includini7 n11 values between *0.6 tne
+1.5
in,,lusive, ari , 1 percent negative all vnnen beter-1.4 an, -0•5 incl'isive. Or this flame rec, e of positive end negative velus was extended to aommt
ell t!Ie f'ree flo obis rvetion, on te 17 27 17 2,-,aLd (8)
P-feet rlumes.
•••••••••••11w
4)
Of the tota, of 3,08 free flou test;-,, t exc2udeu because of grol;:; error, (0512, 3-foot flume, rict 7043, t:-foot31X tusts (7625-3, 7730-40, 2-foot flume, grid 5-26, 3-foot fllme) were excu:40..i. Tests b475-77 wer because the v'lue of Ha exceeded 2.5 feet. 3ummory a.; fo3s:
NO
Test •
H
Ratior nb/Ha
Observ- 7om- ')if f- evi-ed puted eronce ntlon
1.coef
'Feet
—Teet
,ecei4N.7ffec..ft. sec..t.176"Feen
.476 1 2.722 1.795 0477 1 2.641 3.726 MO.^ 0.659 18.13 18.36 -0.23 1. .553 17.34 17.54 - .20 3.' AMP .110111.1.11.11...The heiF,ht, or ordinate of tLo bars in tl,c error diacrtim, fic,ure 4, shows the percentr.ge of total of 298 tests, liA•ted in
heed, Ha, from 0.2 foot to 1610 feet with the Uniting degree of submergence of 69.9 percent. For the distribution of the oriinal 15,2, tests, it was found that a-proximately 97 percent of t17e total number fell within the. limit at i3 percent of .he comruted value of tte discharge; 'hula for te) total 298 tests, 89 percent were within this limit.
hen the seres W* tests, consisting or 139 observations on the 1 2, 41 6-and 8-foot flumes, made at 1e12vue laboratory il 1926, vs included rith the ori7inal tests, n i.cier variation of the devietion beteen Ye otserved rd comp.Ated disehares wtis found to exist. In the orial scTies of 1923 tJIitre went about twice as many tests ruld at the Fort Co:lins hy:Amulic lftboretory, volumetric measur,qacnts, on 1-, 2- an 3-foot flumes, as were ttAkon at the ellvue labor:Jory. The 1926 tests were all mcde at tte T'ellvue laborntor there rectun,Illar weirs, 18 inches, 48 inches an, . 15 feet in
vere sod to deter:line tie observed discharge, (Figure 7)0).
• Table III,
Fixing
the free flov. ischrge in second -feet thrh the - nreAll measuring flume for size fro" „ 1 f(2ot to 8 feet, is . ,7,sed on formula1.52Z:3.020 4,,11
T. -4. .,1144rrertd°.- r tr is Ori-P* .•••
rlgUIND L e-- Aso-foot Peratial moosurin aim on Jones Littera
User Lonrmont, Colorado• nroo-flou dloohargo of
about 0
seoondi•
Figur* 60.4u4.44,lot Parshall manuring flume
disphargelng 5.7
ompord.fest, subLiergencn 50 peroont, loss of head about 0.4 foot,
Mitchell farm lateral nocr Len Anissip Colorado.
TABLE III.--iiVE-YLOW IISUdatU PARVALL MiAi0hINJ
0.026 . 8220v Computed from the forrnttla -= 4143
41
jp,Jer Head IIa
LisgharR9 per seoond for flumes of v ,-,rious throat widths
1 root iet 3 4: aet 4 r eet b :get 6 reet, 7 4 eat 8 eet
r eat Inches t. ft. ,ha. ft. t. ft. Ja. ft. AI. ft. vi.;. ft. ..;14. ft. Jt. ft.
O.0 2 3/8 0.35 O. b6 0.97 1.z6 .21 2 1/2 .37 .71 1.04 1.36 .22 2.5/8 .40 .. 77 1.12 1.47 .23 2 3/4 .43 .82 1.20 1.58 ..&4 2 7/8 .46 .88 1.28 1.69 .25 3 .49 .93 1.37 1.80 2.22 2.63 .26 3 1/8 .51 . J9 1.46 1. /1 2.36 2. .27 3 1/4 .54 1.05 1.55 2.03 -. 50 ... 37 . 28 3 3/8 . L8 1. 11 1. 64 2. lb -. 65 3. 15 .29 3 1/2 .61 1.18 1.73 4.27 2.80 3.33 . 30 3 5/8 . 64 1. 44 1. 82 2. 39 2.36 3. 52 4.08 4. 62 . 31 3 3/4 . 68 1. 30 1. 92 2. 52 3. 12 3. 11 4. 30 4. 88 . 32 3 13/16 . 71 1. 37 2.02 2. 65 3. 28 3. 90 4. 52 t . 13 .33 3 15/16 .74 1.44 2.12 4. 78 3.44 4. 10 4.75 5.39 .34 4 1/16 .77 1.50 2.22 2.92 3.61 'e.30 4.98 5.66 .35 4 3/16 .80 1.57 4.32 3.06 3.78 4. 0 b,22 5.93 .36 4 5116 .84 1.64 2.42 3.20 3.95 '.71 5.46 6.20 .37 4 7/16 .88 1.72 2.53 3.34 '.13 4.92 5.70 6.46 . 38 4 3/16 . 32 1.79 2. 64 3. 48 4. 11 5. 13 E. 95 6. 76 .39 4 11/16 .95 1.86 2.75 3.62 4.49 5.35 6.20 7.05 .40 4 13/16 .99 1.93 2.66 3.77 4.68 5.57 6.46 7.34 .41 4 15/16 1.03 2.01 2.7 3.92 4.86 5.80 6.72 7.64 .42 5 1/16 1.07 2.09 3.08 4.07 b. 05, 6.02 6.98 7.'j4 . 43 5 3/16 1. 11 2. 16 3. 2, 4. 22 5. 24 6. 25 7. 25 8. 24 . 44 5 1/4 1. 15 2. 24 3. 32 4. 38 E. 43 6. 48 7. 52 6. 55 . 45 5 3/8 1. 19 2. 32 3. 44 4. 54 L. 63 6. 73 7. 60 8. 87 .46 5 1/2 1.23 2.40 3.56 4.70 5.83 6./6 8.08 9.19 .47 5 5/8 1.27 ..48. 3.68 4.86 . 6.03 7.20 8.36 9.51 . 48 5 3/4 1.31 2.57 3.80 t. 03 6.24 7. I . b. 65 9. 84 .49 5 7/8 1. 35 2. 65 3. 92 5. 20 6. 4.5 7. 69 S. 94 10. 17 .50 6 1.39 2.73 4.05 5.36 6.66 7.94 9.23 10.51 .51 6 1/8 1.44 ...82 4.16 5. 53 6.87 8.40 9. 53 10.85 .52 6 1/4 1. 48 2. 90 4.31 5.70 7.09 8.46 9.83 11.19 . 53 6 3/8 1. 52 2. Pi 4. 44 5. 88 7. 30 Li. 7L 10. 14 1/. 54 .54 6 1/2 1.57 3.06 itt. 57 6. 05 7.52 8.96 10.45 11.89
1A61.- Ii1 (,Jontin.6o4)
Upper.crge ettoond for flurri..is of var Lou gi throat wiathb
ii
r S. xtitt x est r lost_ .____LoA, 1 r ttet r it .:it reet
Feet Inohme 0u. r t. Ot. r t. ju. r t. j1;. i t. ,A.I. r t. jt. A. t. -•11. 4 t. ,•;11. it.
6310. 6.30 6. 23 7. 74 4. 26 10.76 12. 24 4. 84 9. L2 11.07 12. 60 6. 9a7096 07 11. 71 13. 33 L. 26 6. /6 8. 66 10..35 12. 03 1.3. 70 L. 39 7.15 6. 89 10. 63 12. 36 14. 08 10. 92 12. 60 16. 46 E. 6611.20 13.02 14. 84 61 11. 49 13. 36 16. 23 2.. 97 7. -91 9. St 11. 78 13, 70 15. 62 6. 12 3.11 10. 10 12. 08 14. 05 16.01 6. 2638 14. 40 16. 41 6. 41 8. Li 10. 59 12. 68 14. 75 16. Si 6. E.6 S. 71 10. St 12. 98 16.10 17. 22 6. 71 8.10 13, 28 15. 46 17. 6.3 6. 86 .9.11 11. 36 13. L9 15. 82 16. 04 7. 02 9. 32 11.62 13. 90 16.18 16. 45 7. 17 9. b3 11. 88 14. 22 16. Lb 15. 87 7. 3.5 9. 74 12.14 14. 63 16. 92 19. 29 7. 49 i. 1 t., 12. 40 14. 85 17. 29 19.71 7. 66- 10. 16 12. 67 16. 17 17. 66 2.0. 14 38 12. 94 16.04 20.67 60 13. 21 16. 82 16. 42 21.01 6. 13 10. al 13. 48 16.16 18. 61 21. 46 8. 30 11. 03 13. 76 16. 48 19. 20 21. /1 8. 46 11.25 14.04 16. Si J1. b/ 22. 36 8. 63 11. 48 14. 32 17. lE 19.99 22. 81 70 14. 60 17. 49 20. 39 23. 26 8. 96 11. 92 14. 88 17. 63 20. 79 23. 72 9. 13 12. 15 16.17 18.17 21. 16 24. 18 12. 36 16. 4i) 16. 62 21. 66 24. 6.4 0. 48 12. 61 1E. 76 18. 87 21. 9/ 25. 11 9. 6516.04 1/. 22 22. 40 21. 68 0. 82 13. 07 16. 33 19. b7 2-.82 26.06 10.00 13. 31 16. 62 19.13 23. 24 26. 1 4 10.17 13. ft 16. 92 zo. 29 23. 66 27. 02 36 13. 79 17. 22 20. 65 24.08 27.50 10. L3 14.03 17. 62 21. Ul 24. 60 27.99 10. 71 14. 27 17. 82 21. 38 26. 93 28. 48 89 14. 51 18. , a 36 28. 97 O. 55 670 . 66 6 3/4 1. 66 3. 26 .57 6 13/16 1. 7096 16/16 1/16 1. 60 3. 63 . 60 7 3/16 1.84 3. 62 . 61'9.13 . 62 7 7/16 1.13 3. 81 . 63 7 0/16 1. 98 11/16 2.03 4. 01 . 65 7 13/16 2. 08 4. 11 . 66 7 15/16 . 67 5 1/164.. 30 . 66 8 3/16 2.3 4. 40 . 69 8 1/4 2. 28 4. 60 . 70 8 60 38 4, 70 . 72 3 L/S Z. 43 4. 81 . 73 6 3/ 4 L. 4.8 4. 91 . 74 6 7/8 2.63 . L.02 . 76 9 2. L. S 6.12 . 76 9 1/8 2. .77 910. . 76 9 3/8 2. 74 5. 44 bb
.ao
4 6/8 2. 65 b. 66 .81 9 3/4 2.10 L. 77 16/16 3.02 6. OC .84 10 1/16 3.07 6.11 . 85 10 3/16 . 66 10 5/16 3.16 6. 33 .87 10 7/16 6. 64 0/16 3. 9a L6 11/16 6. 68 .90 10 13/16 3.41 6. 60 . 91 10 15/16 3. 4610. .12 11 1/16 3. 52 7.03 . 93 11 3/16 3. L8 7.1E: 6410.Upper a
Head DIou.rge pair act uon0 fcr flunat3a cf vf_lr iot 6 threat mid the
1 z oot 2 z Set 3 r eat iet 5 0:7A 6 4` eat 7 llt
ieet. inallas 014. ft. 0u. ft. .;t2, ft. 0u. ft. ..A... ft. du. ft
_et 06. ft. 0,-. ft. 0./5 11 3/8 3.70 7.3i 11.07 14.76 18. 44 22.1.. 3L?8 29.47 .96 11 1/2 3.76 7.51 11.26 15.00 16.75 22.4/ .97 11 5/8 3.82 7.63 11.44 15. 25 19.06 22.86 26.66 30.8 .98 11 3/4 3.88 7.75 11.63 15.50 19.37 2.3.24 27. 10 30. /8 .9) 11 7/8 3.94 7.38 11.82 L.75 19.68 23.62 27.55 31.49 1.00 U. 4.30 8.00 12.00 16.00 20.00 24.00 28.00 32.00 1.01 12 1/8 *.0S 8.12 12.19 16. -5 2O.32 4.382 26. 45 32. 52 1.02 12 1/4 4. 12. 9.25 12. 38 16.51 20. 64 24. 77 26. )0 33.04 1.03 12 3/8 4.. 18 8.38 1..&7 1.76 0.962 25.16 9.362 33.56 1.04 12 1/2 4..5 8.50 12.76 17.02 21.28 2.5.55 29.92 34,08 1.05 12 6/8 4..31 3.63 12.36 17..8 .1.61 25.14 30,28 34.61 1.06 12 3/4 4.37 8.76 13. 15 17.534 21.94 26.33 30.74 35.14 1.07 1... 13/16 4. 43 8.88 13.34 17.80 22.2? 26.74 31.20 35.68 1.08 12.15/16 4.50 9. 01 13.b4 13.07 22.60 27.13 31.67 36.22. 1.09 13 1/16 4.56 9.14 13.74 18.34 22.13 27.53 L.14 36.76 1,10 13 3/16 4.62 9.27 13.93 1.63 23.26 27.94 32.62.37.30 1.11 13 5/16 4.68 9.40 14.13 18.86 23.60 2 J. 35 33.10 37.94 1.12 13 7/16 4.75 9.54 14.33 1.13 23.94 28.76 33.53 38.39 1.13 13 9/16 4.82. s.67 14.53 19.30 24.28 2'9.1? 34.06 38.94 1.14 13 11/16 3.88 9.80 14. 73 1 /. 67 24.62 2.58 34.bNi $.b0 1.15 15 13/16 4.9* 9.91i 14.94 1.94 '4.96 30.00 3b.02 40.06 1.16 13.15/16 5.01 10.07 15.14 2O..2 5.312 30 . 41 35.51 40.62 1.17 14 1/16 5.08 10.20 15.34 20.50 25. 66 30.83 36.00 41.18 1.18 14 3/16 5.15 10.34 15.55 40.73 Z6.01 31.25 36.50 41.75 1. 19 14 1/4 5. 21 10. 48 15. 76 21. 05 26. 36 31. 68 37. 30 42. 32 1.60 14.3/8 5.28 10.61 15.96 21.33 26.71 32.10 37.50 42.89 1.21 14 1/2 5.34 10.75 16.17 2.1.61 27.06 32.53 38.O 43.47 1.22 14 6/8 5.41 10.8) 16.38 21.90 27.46 32.96 38.50 44.05 1.3 14 3/4 5.48 11.03 16.60 22.18 27.73 33.39 3:J.00 4.64 1.2.4 1. 7/8 b. Set 11.17 16.81 22.47 2.8.14 33.82 3.51 45.22 1.25 L. 5.62 11.31 17.02 22,75:28,50 34.26 40.02 45. 60 1.46 15 1/8 L6.; 11.45 17.43 23.04 2.36 34.70 40.54 46.39 1.27 15 1/4 5.76 11.59 17. 4 , 33•33 29.22 35.14 41.05 46. 97 ]...8 15. 3/8 5.82 11.73 11.56 Z3.6. 29.59 35.58 41.57 47.57 1. 29 lb 1/2. 5.89 11.67 17.88 23.92 2. 96 36.02 42.09 48.17 1.30 lb 08 5.96 12.01 18.10 24.21 30.33 36.47 42.62 48.79 1.31 lb 3/4 6.03 12.16 18.32 24.50 30.70 36.92 43.14 4.38 1.32 15 13/16 6.10 14.30 18.54 24.80 31.07 37.37 43,67 49.99 1.33 15 15/16 6. lo 12. .4 18.76 25.10 31.'e A 37.82 44.20 50.60 1. 34 16 1/16 6..5 1.. 59 16. 96 26. 39 31.82 38. 28 44. 73 21. L2 1.35 16 3/16 6.32 12.74 1.20 25.69 32.20 38.74 45. .4 51.84 1.36 16 6/16 6.3/ 12.89 19. 42 2L9 &.58 3.20 L.80 52.46 1.37 16.7/16 6.46 13.03 1J.63 26.33 32.38 39.66 46.35 53.08 1.38 16 9/16 6.53 13.18 1.67 26.60 33.34 40.12 46.89 53.70 1.39 16/11/16 6.60 13.33 20.10 26.90 33.72 40.58 47.44 4.331,,
Upper H
s
3esa It so 4L_Age 1,er **Gond f I'ltissis of var toys throat Ai dths
1 3 4 keet Zdt 449t b t tot( 6 rQt 7 iotOt 8 /set • ot,
Lashes „Ai. ft. J6. ft 3A.,. ft. ;L. ft. .:14. ft. ft JL. ft. 31... ft.
1.40 16 13/16 6.68 13.48 20.& 27.21 34. 11 4i.0.. 47.99 1.41 16 15/16 ó.7b 13.63 30.t 27. 52 1.LC 41. 52 • 55. 58 1.42 17 1/16 6.2 13.78 20.78 27.82 34.81 41.11 49.09 £4.22 1.43 17 3/16 6.39 13.13 4.01 48.11, 3t..28 4.46 49.64 £4.36 1.44 17 1/4 6.9? 14.08 21.4 28.4b 35.67 42.94 50.20 L7. 50 1.'.5 17 6/8 7.04 14.23 21.47 28.76 36.06 43.62 50.76 £8.14 1.46 17 1/2 7.12 14.38 21.70 29.07 36.46 43.89 I 1. 32 £8.78 1.4? 17 £/8 7.19 14.54 21.94 ..9.38 36.66 44.37 51.83 £9.43 1.48 17 3/4 7. 26 14.69 22.17 2.1.70 37..6 44.85 52. 45 60.08 1.4w 17 7/8 7.34 14.36 22.41 30.02 37.66 4L34 t3,0. 60.74 1.50 18 7,41 15. ki0 £2.64 30.34 38.06 41-. 82 £3. 59 61.40 1. 51 13 1/8 7. 4/ 1.. 16 22. 88 30. 66 38. 46 46. 31 f 4. 16 62. 06 1.52 18 1/4 7, 7 15.31 23.12 30.98 36.87 46.60 b.74 6.74 1.53 16 3/8 7.64 15.47 23.36 31.30 39.26 47.30 55.32 63. 38 1.54 18 1/2 7.72 15.62 2.3.60 31.63 3.68 47.79 55.90 64.04 1.55 18 tfa 7.80 15.76 23.84 31.t 40.09 46.28 46 6.71 1.56 18 3/4 7.67 15.94 24.08 3.27 40.51 48.78 £7.06 61.36 1.57 18 13/16 7.95 16.10 24.32 &.60 40.92 49.28 57.65 66.06 1.58 13 1516 8.02 16.26 24.56 .52. /3 41.33 49,78 59,4 66.74 1.59 1/ 1/16 8.10 16.42 24.80 33.26 41.75 50.28 58.$3 67.42 1.60 19 3/16 8.13 1.56 2b. 05 33.59 42,17 t,7' 59, 42, 643. 10 1.61 19 s/16 8.ó 16.74 25.30 33.92 42.59 51.30 60.02 68.79 1.62 1r 7/16 8.34 16.90 25.54 34.26 43.01 1.81, 60.62 6.46 1.63 li //16 6.42 17.06 2.5.79 34.60 43.43 52.3.. 61.22 70.1? 1.64 19 11/16 8.49 17.24 26.04 34.93 43.86 52.83 61.82 70.66 1.65 11 13/16 8.57 17.38 26.2/ 3L...6 44.28 53,34 62, 42 71.56 1.66 1/ 15/16 8.65 17.55 26.54 35.60 44.70 53,86 63.03 7.26 1.67 20 1/16 3.73 17.72 26.79 32.94 45.13 5'.38 o3.64 76.96 1.68 20 3/16 6.81 17.68 27.04 36.28 45.56 54.90 64.5 73.66 1.69 20 1/4 8.89 16.04 27.30 36.62 .ó..0 55.a2 t,66 7a.37 1.70 20 3/8 6.97 18.41 97•55 36.96 46.43 5L95 6L.48 75.08 Li). 20 1/2. /. 05 1.33 27.80 37.30 46.86 56.48 66.10 75.7 1.72 20 1,18 9.13 16.54 28.06 37.65 47.30 b7.0( 66.72 76. 1.73 20 3/4 9.21. 18.71 26.32 38.00 47.74 57. 53 6 7.M 77. 2-1. 74 20 7/9 9. 29 16.83 28.57 38.3* 48.17 58.06 67.9k ??,9t 1.75 21 9.33 14.04 28.32 33.69 48.61 58.6.68.59 78.66 1.76 21 1/8 9.46 19.21 29.08 3/.04 4.0L 59.13 69.22?'i.38 1.77 2.1 1/4 9.54 19.38 29.34 39.39 49.0 59.67 6.8b SC. 10 1.78 21 3/8 9.62 19.15 29.60 39.74 49.94 60.20 70.46 90.33 1,7/ 21 1/2 9.70 19.72 29.07 40.10 50.38 60.74 71.11
TABL2 111. --( '4ont Inued jp.p er 4-1. eau
H a
I, i62qr,rge -q. 6-_-;cond for flumes cf v -_,.r tout, throat Ticiths. 1 z Oot 2 teat ti s tiot 4 iwit b :feet 6 itl.A. 7 z eat 6 'telt
Lao
za Lye
9. 79 19. JO 30.13 W. 45 50. 83 61. 29 71. 75 82. 29 1. 81 21 3/4 J. 87 20,27 30. 39 40. 80 61. 26 61. 66 74. 39 63.03 1. 82 21 13/16 9. ib 20.724 , 30. 05 41. 16 51. 73 62. 35 73.03 83. 77 1. 83 21 ib/16 10.04 20. 42 30. 92 421.. tdk. b2. lb 62.92 73. 68 84. 61 1. 84 22 1/16 10. 12 20. 59 31.18 41. 85 61 63. 46 74. 33 86. 26 1. St) 22 3/16 10. 20 20. 76 31. 45, 42. -4 L3.0 64. 01 74. 96 86. 00 1. 86 22 5/16 10. 20. 93 31. 71 42. 60 b3. bb 64. t7 7b. 63 36. 75 1. 37 22 7/1621.10 31. 96 42. 96 b4. 00 61‘,. 13 76. 48 87. 6,0 1. 38 22 1/16 10. 46 21. 28 3%. 21., 43. 32 b 46 61,. 69 76. 93 88. 25 11/10 10.46 32. 52 43. 6966.25 77. be 99. 00 1. 90 22 13/16 10. 6279 44. Of 56. 39 66. 81 78. 4 89. 76 1. 91 22 15/16.I 33.06 44. 42 EL. 8t 67.90 1. 92 1.3 1/16 10. 80 21. 99 33. 33 44. 79 56. 32, 67. 9:3 79. 56 91. 29 1. 93 23 3/16 10. 88 22.17 3,'. 60 44.16 66. 78 63. LO 1. 94 23 1/4 10. 97 22. 33. 87 -it, . 53 57. 25 69. I. 80. 90 92. 82 1. 96 23 3/8 11.06 22. 63 34.14 45. 30 b7. 72 69. 63 81. 57 93. t 9 I. 96 23 1/2 11. 14 22. 70 34. 42 4-6. 27 tii. 1 70. 20 82. 24 94. 36 1. 97 ::3 b/8 11. 23 22. 88 34. 70 46. 64 66. 67 70. 78 8_ 91 9t. 14 1. 98 22i 3/4 11. 31 23.06 34. 97 47. 02, b9. 14 71. 36 83. 68 96. 92 1. 39 23 7/8 11. 40 23. 24 3t. 25 47. 40 59. 61 71. 9284.
26 96. 70 2. 00 24 11. 4J 23. 43 35. t3 47. 77 60. 08 72. 50 84. 94 97. 4f3 2.01 24 1/8 11. ES 23. 61 35. 81 48. /4 60. 66 73. 08 85. 62 98. 26 2.02 24 1/4 11. 66 23. 79 36. 09 48. 62 61. 04 73. 66 86. 30 99. 05 2.03 24 3/8 11. 75 23. 99 36. 37 48. 90 61. 52 74....4 96. 9'9 99. 84 2. 04 24 1/2 11. 8 eit 24.16 36. 61: 49. 29 62. 00 74. d3 67. 66 100. 6 2. 05 24 5/8 11. 93 24. 3-* 36. J4 49. 67 46 75. 42 88. 37 101. ik 2. 06 24 3/4 12.02 24. 52 37. 22 60. 05 62. 97 76. 00 89.06 102. Z. 07 24 13/16 12.10 24. 70 37. 50 50. 14 63. 46 76.1-.9 89. 75 103. 0 2. 08 24 lt/16 12. 19 24. 89 37. 78 50. 82 63. 94 77. 19 90. 44 103. 8 2.09 26 1 16 12.28 25.08 38.06 bl.;r..1 64. 43 77. 78 91.14 104.6 2.10 25 3/16 12. 37 2L. 27 4.3':). 3: 51. 69 64. a 2 76. 37 91. 84 10E. 4 2.11 2.6 5/16 12. 46 2L. 46 38. 64 61. 98 6b. 41 78. 97 92. 54 106. 2 2.12 25 7/16 12.55 o I 38. 93 52. 37 6E. 91 79. 56 93. 25 107. 0 2. 13 2t 9/16 14. 64 . 39. 22 2. 76 66. 40 60. lb 13. 96 107. 9 2. 14 25 11/16 12. 73 -6. 01 3J. 60 E3.1:. 66. 89 BO. 75) 94. 66 108. 7 2. 15 .46 13/16 12. 82 26. 2.0 39. 79 53. L4 67. 39 81. 36 95. 37 109.5 2.16 2t 15116 12. 92 2,6. 3.) 40. 08 t3.14, 67. 89 81. 97 96. 08 110..5 2.17 26 1/16 13. 01 26. 58 40. 37 54. 34 68. 82. b8 96. 71 111. 1 2. 18 26 3/16 13. 10 26. 77 40. 66 64.73 68. 89 83. 19 97. 51 111.) 2. 13 2.6 1/4 13. 19 26. 96 /6 Lb. 12 6/. 31 83. 80 /8. 23 11.2.. 8r123L2: III. ( Continued )
i.tsohx'ge Ltsoonci for 2122218 of Yuri oue throat lthitile Upper Read H a 1 .i'oot 2 e ile,t 3 boot 4 ieet 5 rclet 6 z -set 7 2 eet 8 24et._
Feet Inohee 22-2 ft. Ju. ft. Cu. ft. ju. ft. Cu. ft. ..4 . ft. C2. ft. Cu. ft.
2.20 26 3/8 13.28 27.15 41.21 15.52 69.90 84.41 98.94 113.6 2.21 26 1/2 14.37 27.34 41.14 52.9- 70.40 81.02 .6..., 11.4 '4.24 26 b/8 13.46 27.124 41.84 16.32 70.90 81.63 101.4 115.3 2.23 26 3/4 13.56 27 . 7 3 42.13 56.72 71.41 36.25 101.1 116.1 2.24 *46 7/9 13.65 17,92 42. 43 /7. 12 71.92 86.87 101.8 116.9 2.25 27 13.74 26.12 42.73 67.5.. 72.43 97.49 102.6 117.13 2.26 27 1/8 13. 84 28. 31 43.02 57. 93 72. /4 88. 11 103.2; 118. 6 2.27 27 1/4 13.93 28.50 43.32 58.34 73.4k 88.73 104.0 119.6 2.28 27 3/8 14.02 28.70 43.62 58.74 73.97 09.35 104.8 120.3 2.29 27 1/2 14. 12 2.8.10 43.92 59. 15 74.49 69. 98 105.5 121. 2 2.30 27 5/8 1*. 21 29.09 44.22 69.56 75.01 90.61 101.2 122.0 2.31 27 3/4 1.30 28.29 44.52 59.16 71.53 91.24 107.0 2.32 ..7 13/16 i4.40 29.9 44. 83 60.37 76.01 91.87 107.7 123.7 2.33 27 15/16 14.4/ 29.69 45.13 60.79 7h.57 92.10 108.1 124.6 2.34 28 1/16 14.59 29.89 4b.43 61.20 77.0/ 93.14 109.2 121.4 2.35 28.3/16 14.68 30.08 45.74 61.61 77.61 93,77 110.0 146.3 2.36
28
5/16 14.78 30.28 46.04 62.03 73.13 M.41 110.7 127.2 2.37 28 7/16 1.87 30.48 46.3k. 62. 44 78.66 95.06 111.5 1.8.0 2.38 28 //16 14.97 30.69 46.66 6...86 79.19 96.69 114. 4 128.9 2. 39 . 8 11/16 15.07 30.89 46. /6 63.27 79. 72. 96. 33 113.0 12/. 8 2.40 2.8 13/16 11.16 31.09 47.27 63.69 80.25 96.97 113.? 130.7 .41 28 11/16 15.26 31.29 47.b8 64. 11 30.78 97.62 114.5 131.5 2. 42 29 1/16 lb. 31 31. 4/ 47. 89 64.53 61. 31 /8. 27 115. 3 132. 4 2.43 29 3/16 12... 4I) 31.69 48.20 64.9L, 81.84 96.91 116.0 133.3 244 29 1/4 11.15 31.89 48.11 61.38 82.33 i .,. 52 116.8 13i. 2 2.46 29 3/8 15.64 32.10 48.82 61.80 8.i2 100.2 117.6 13.1 2.46 26 1/2 15.74 32•3Q 49.13 66.23 83.41 100.9 1113.3 13L9 2.47 29 518 15.89 32210 49.46 66. 6583. 99
101.5 119.1 136.8 2.48 29 3/4 15.94 3-.70 4.76 67.07 84.3 102.4 119.9 137.7 .49 21 7/8 16.03 3...90 50.08 67. bC, 85.07 102.8 120.6 138.6 2.10 30 16.13 33.11 50.3/ 67.13 81.62 103.5 121.* 139.5
-20-a-2-foot Parshall measurinF flumes oTerntin under free flow corditions, the latter one bein e ui .0 with a water-stage recording instrument givinr a record of the upper hend, 7
a There 1:3 practically no I;ubmergence in the case of the 1-foot flume, in the 2-foot structur te cer,ree of submergence is approximately 50 -ercent for discharge of 5.7 second -feet. The loss of he ir this structure was determined rou hi: in the field to be about inches, 'nd 1D ap lying t!.e eta to the diagram, figure 18, the loss
Is calculated to be 5 inches.
The loss of hea. as referred to in this discussion, is taken as the vertical distance in feet between the wtiter
surfaces at the upstre and dowLstre.. ends of the structure an - does not represent the total loss jr head because the velocity heads of the info in aru outflozirp: stream through the flue have not been considered..
submerged 'low Formula
In the development of a formuli: suitable for the
determination of discharge throu,7h the Parshall 7easurinp flume for s'ibmerged flow, various methods vere atte..pted, a for of equation being s_urtt that tould folio consistent-ly the trend of the data and at the same ti e not be so
complicated as to be impracticable. The following was the manner of re:esoninc finall followod:
)r the degree of subbkergence below 70 percent, it is found the a si ;Tole exprssior till apply in determining the rate of discharge where only the upper head, Ha, an. the width of th flurae are involved. lioLever, Olen the degree
20b-of submergence is 70 percent or more the free flow dischare is diminishe slightly at fir:it, and Es the—,:egree of
submergence increases, the rate of decrease in flov is incresed until, er th point A‘ comlete subr-wrgerce, the noir is very 1:.,reat1y reduced. The detemination of
the rate of suberged flow is then brised upon the application of a certain (:orrection to the free flov, for tLat particular head, H5 , and the corresponding ratio of the throat head to the upper head. As pointed out, this ratio must be
...51411.11
rrhe e:nrittn1 nt upon w.11.1,7!
basee incleed 'InE‘ r - Er11 - 3 f 1), t 7.rde in 1923, .here t„he '41 or sIbmen7erce fr17.! 70 to ncre thou 95 pe7mt, rrIne of Ti
a fro C. foot to
921-t!inn 2.5 feet. Tey sr divtied acccrdin to size of flume ns l'ollon; 1-foot flu, 46 tosts; 2-foot flunc,
A. teats; :7.-foo l'2,111e, 65 tests; 4-foot flume, 21 tot; 6-foot r1ue, 1L tf;sts, and 8-foot flum, 37 tents. In 1926 a serins of submerged flow tests, numberinc 254,
ard when the results were compared it thn original subnorgence date it was found that a slirht adjustment in the correction was necessary. The combination of all the submerged flow tosts shoes the foiloAng division eecordinF.: to size of .flume: 1-foot flume, SO tests; 2-foot flume, 84 tests;
-foot flurne, 61 tats; 4-foot flume, 64 tests; 6-foot flume, 85 tests, r.rd. P-foot Mime, 116 tests. In the final
EirruLe-(9) merit 21 ':ess were exclu(lee fro. the 1923 series.
For t e 1-foot flue, te:A 8494 excluddd because !la exceeded 2.5 feet. ';'ests 6656-57, 6707-01excluded bect;le Ha 0.2 foot. Tests G6P41 6700, 6705 excluded because
submerenc exceeded 95 7-Aercents V:e 2-foot flume, test 624 exA.uded buct;use sub. rgerice excooded 95 preent, ests t;642-43 f1/11 6646 excliWed beciAlse ha 0.2 feet; 3-foot flume,
test
£583 excluded beenuse submcrgenJo exc.. ed 93 percent, and tests 6579-80-81 excluded because lie C.2 foot; 3-foottests 6342 and 7079 excluded because submcrgence eceeded 95 percent; 8-foot flue, tests 7020.49 excluded
-22-laow tests fallin vithin the prescriued limits, test 63:55 excludeci bec'aise of gross error.
....0101.11110111011.11.1.1..
.fter rev1ew1nr tu con:Inc:id series it was found that f3r sulyergence, where te gal7e ratio 1.11::a exceeded
C.95, little dependence could be pinced upon the accurncy
of -nn.:ted disclarr,e; 'e vnlue of !la 'as
0.2 foot, the: deviation bet%een the o7served and computed dischari,70 was quite large. In the use of a more complicated ex7roio :icteyination f thr corection :'actor
4-A. uL 1)o poti1b3e to reduce VI error for these lo'
but fo 111-1' sIll'ererce at onv hea Has obs(rveti - ns sho .':Inrked inconsistencies.
1,ese dat were plottod as shown In ricure 7, vhere the several curved lineb ':43-re;:ient the degree of subrAergence.
r any particul . r point on the :A.Coergence line tLere will be n definite vc,lue, 0, as shov4n, which is amount in
second -feet to be subtractei froca tc; free flo value for that partiidlar .;per he6d, Has t ve the submerged flov. It will be observed that as the value of Ha incresed, the amount of the correction also increases for an particular
degree or subrxrgence. It is found that for the re2otion e istinj between the correction ftctor)C)for submergence an:. the upper head, 1 /1, for any depree of Eubmergerce, the Feneral e)mresion e statA thus:
ii C
0.9 .3(3 '• e•S< Tee -0.8 l'C'e ,---1.-1 0.7 Ok ;:-..°44°°P % ge' i 0.5 0.4 . D.3 4e4e 0.2 .0 3.0 4.0 5.0 DISCHARGE SECOND - FEET
6.0 7.0 8.0
negro
7.-- mainir or oorrettlon factor. C.In Second-feet, to be subtracted from the
from
flow
dlwoharge for n definitevalue of na
anda certain degree of submergcnee*
25 2.0 A
f
91";10" It. 16 ' 7,0 0 '306 07 0809 JO 25 .15 175 2T
25 .3 .35 4 5 6 7 .8 9 10 125 15 175 2 25 3 35 443 5 6 7 CORRECTION -CUBIC FEET PER SECONDCs
Figur* C.--Olsgram for corrtitinA'; submerm04 now through 1.400t Partrell --dettn;Jr111; flume.
-23-where Ck is the correction in secon,j-feet for the degree of subliergence K, expresse as a decimal fraction, and He upper heed in feet. J and B are values dependent on the
gage ratio or decree of submergence, -I, and n an exponent also depend on K. Base equations were developed for various values of ranging from 0.70 to 0.95, and from these
the law of variation of A, and n was determined. This relation for t7.e 1-foot flume is as follows:
Ha
Ck= 1.8
1.E.4
—2:45
+0.093K
For the other sizes of flume it was found by introducing a multiplyin- factor to the value of C thnt a practical agreement A.th the observed submerged flow was nossible. This factor, M, varies with the vidth or size of flume,
0.815 according to the simple relation M
The follo‘int: is the complete formula for computing the discharr,e through the arshall measurint flume for suber,-ed flow: 1.522W a 4.b7 -. 3.14K He 1.8 —2,43 K j +0.093K
This formula is not, in It complete statement, , simple expression; hov;ever, when the value of K, the degree of submergence expressed as a decimal fretion, 12 properly substjtuted, the formula, or that term rcpresentin- the correction C, becomes much simplified.
PER CENT OF TOTAL NUMBER OF TESTS 18 16 14 12 10 8 7 13 12 in El n 11 10 9 8 7 6 5 4 3 2 NEGATiVE 0 1 2
7
34PER CENT DEVIATION 5
n FLE, ri_Fl
P726 7 8 9 10 11 12 13 POSITIVE
ure 9.--Comperlson in percentage of computed
to observed submerged floe discharges through
experiental flumes*
To fncilitFte the. use of this submerged flov correction farmula vnllles of C for 1-foot flume may be tilkon. directly fre7 the diagram, figure .S determine the submergeS flo correction for other sizes of flume
multiply this correction by thn factor, M e ns given in the
fo)icr:inr! tbillrItion, before subtrncting from ti.e corresponding free .4 low for tnt 7articular Ha head.
3ize of flume ultiplying factor :ize of flume :Iultiplying factor
.N.1.••••
;717i77761---
..
in feet1 1.0 5 3.7
2 1.8 6 4.3
3 2.4 7 4.9
Figure shows the agreement of the observed and computed discharges for submerged flow. The manner of copiling the date and constructin this diagram is identical with thrt given for the free flow discharge. In the comarison of computed and observed discharges for the tutal 470 tests, it vas found that 87 percent were within 5 nercet f the observed vnlue.
In the eompnrison of the free flow nnd submerged flov error diagrams, it is evident t..t the accuracy of the measurement 7renter .,:rlere the ,;eviee operate:, under a free flow condition.
To detemine the (ritiv- of dischari7e throwt the 7ershall measuring flume under submered flcm t - following examples are given to illustrate the method of computationt
(1) Let it be assumed th - t the flume has a throat widfk • of one foot; 'Ipp(ir hed, ' 1.50 feet, and the throat be9d
P
1, 1.29 feet. The ratio 1.20/1.50=0.'10. .JAer diegram, fieure 0,at the left hand side on the 7e line 1.5, follow this horizontal line to the eigbt until re!lchirw the curved line
•eo".
7ertical1y beneeth this intersection observe the ree:ire 0.71 which is the correction in second-feet due to the submergence. In the free flow discharge table III for the 1-foot flume with the recorded heid, Ha, of 1.50 feet, note that the discharge is 7.41 sec feet. Theflow with a submer;7ence of 80 percent uner Veee comAtions, will, therefore, be 7.41 - 0.71e 0.70 second -feet.
(2) What will be the disceele7c through a 4-foot flume where the ueeer head Ha 1.6 1.98 feet and the throat head, 141), is 1.60 feet? The l'atio 1.60/1.98 is very closely 0.91. before enter the correction diagren at the loft, however, in this case follow te tbe right alorp- the horizontal line iridiceti..r T0 w 2.0 until te noint le reeched midway betweer curved lines 90 and 92. It is to be kept in "Ind that the line 1411 = 2.0 is above the true velue of the unner hetT 7:blich is 1.98 feet. kt this corrected i)oint move verticelly downward to the bese of the diagram end estimate the value on this scale at 3.50 second-feet which is to submergence correction for e 1-foot fl"Ine. It vAll be noted in the erevioue tabulation thnt the
factor, for zi—foot flume is 1. This rector times ti correction in second-feet is 10.85 second-feet or tIle amour'', to be .deducted fro. t e free flow throut77r te, 41-foot flume for ne ueper heed. He of 1.98 feet. The comeuted
-26-(3) 3uppose the u;:per h_., of an 8-foot flume is 0.69 foot and the throat head, b, is 0.60 foot, what tould be re submerged flow discharge? The retie of tl*e
two heads will be G.60/9.69 or very close].: 0.07. As before enter t- correction diegre at the left a fcllot horizontally to the r1'ht on the line 0.7 to a point about midway bettem the curved lines 86"and
ee..
Since the value of the Ha head is 0.69 foot it will he neces.3ary to select the true pointa'uo'!t one-tenth the intervnl bel_ the o.7 Ha line. Vertically bF,lo thin final location of the true oint there -ell be
found, on the bnse of the diarrram, the vLlue of 0.41
second-feet as the correction for submergence for thc 1-foot flu-le. The mu1ti, 1;,,...nc factor, 7.", for the 0-foot flume will be 0.41 tines 5.4 or 2.21 secel,fect. he free flow
dischtirze through the 8-f ot flume for C.. pper
at C.6(,.. fLo' is 17.60 second-feet. Tho cor.17,to sutl_crged flo: 1, - 15.42 seconc-fet. ,P this
degree of subier enc€ ii is rue,:i1;. e.et,erodt free flov. uischar,e Lao bcz:n reduced a,.proxiiatey 12.5
percent.
The error in calculatin the submer6ea flow Cliscliarge reltinc from observinc either the upper helL.: or the thrc,ut head 0.01 foot to larfse or too snail 1:„ fou;. to be fr :a heads of C. foot Edic, sul.Lirgences to
perc4-:nt to r e frot. about 1 to 10 c,rcent vh1l. for VS 'or, ce Ibis erIor ,e 0 to 00 percent. .ror Tia heads ,.); c,,o,,„ 2 fet this eri. r ftzb'turgonces,
Ylgura 114.0*;lxv.foot Parshall meetsurIN; fluLle stowing a diseharge
of 3* second-feet *1th t submergence of 95 percente oaq Fords
Coloraac.
TABLE 1-1/ .--0011-ASIziON Oi CaLFUTZD DISGHAW& TITROUGH A 6-2J0T rAaR„LL &Lat.:: ;ITN TILT DMRVIL:4:
3r
It-AN.iOF .1 DIJCH,,RGE GURU rJr No:,D1NAZY 7I0J.KY foal DITJH, YORD.
Late
(Thd values of Ha and
t d d m at
Six -loot ParshaIl ilea Burin Fiume
Hb aro s Ingle observe:A 021S;
n f t
Ratio Loss
Hbfila of ch7Jrge
Head
that Is , the; as%$ not the m.)an of
4.A.Unt*
t f
ulage 1.1.60harv erence Levi-at Ion
sevar41 trl .18 Ourrent Meter c;ag-Inge in Rating
471ume **
Ha E
d Ctago B I atz rge
1924 ieet iset feet ;;ec. ft. i eet Leo. ft. iset atm t aet ft.
3/29 1.78 1.68 0.10 0.944 42. 4 1.40 40. 2 +2.2 5.5 3/29 1.73 1.65 .08 .954 0.12 38. 6 1.40 40.2 -.16 4.0 .11.. +meows. 3/30 2.16 2.05 .11 .949 .15 56.7 1.83 54.0 +2. 7 5.0 4/1 1.77 1.70 .07 .960 38.0 1.43 41. 3 -3. 3 8.0 dn... OW.. 4/2 1.26 1.22 .04 .966 .05 min 0.59 24.9 411111...• WW1. von.. 4/9 2.31 2.21 . 10 .957 . 18 61.1 1.99 59.t, +1. 6 2.7 4/11 2. 35 2.20 .15 . 936 . 17 68.2 2.00 59.7 +8.5 14.2 4/21 2,31 2.21 . 10 . 967 .18 61. 1 1.9 59.5 +1. 6 2. 7 ono SO .0. 4/26 1.88 1.77 .11 .941 .11 46.9 1.53 44.3 +2. 6 5.9 .10 4/29 1.50 1.44 .06 . 960 .02 29. 1. 1J 33.8 "4.3 12. 7 min 6/6 1.74 1.66 .08 .954 .11 38. 7 1.41 40.5 -1.8 4.5 ••••••••••• L/6 1.69 64 .05 .970 . 10 1. 37 39.3 _ 1.40 40.3 5/12 1.84 1. 80 .04 .976 .12 1.68 49.1 1.68 48.2 5/29 2.11 2.00 .11 .946 .14 54.8 1.76 51.8 +3.0 L. 8 1.76 51.8 7/9 2. 62. 2. 6'4 .10 .962 .18 .111.110 2.38 72. .0.11.1. 2.38 73.b 7/10 2.99 v.87 . 12 . 960 .18 WO We.. OS 2.70 63. 4 Oft 00 .111. 2.70 83.2 V19 Z.74 Z. 62 .12 .957 . 1=6 0111.1. 2.46 75.3
10/6
1.88 1.77 .11 .941 .11 46.9 1.53 44. 3 t 2. 6 j10/8
2.14 2.04 .10 .953 . 14 54.7 1.67 55. -O. 8 1.411/26
1.92 1.84 .08 . 958 47.1 1.60 46. 6 +0. 1.112/2
12/3
1.95 2.36 1.85 2.25 . 10 .11 .949 . 964 .07 .11 44. 9 63,7 1.6L 2.05 .47. 0 61.3 -Z. 1 +2.4,4,5
3.912/4
12/11
2.22 2.17 2.13 OS .09 .09 . 969 .959 .11 .13 57.0 541.5 1.92 1.85 57.0 • b4. 8 0.0 -O. 3 0.0 0.5 1926 9/28 2.16 2,05 .11 .949 .08 56.7 1.86 65.0 +1.7 3. 1 re. ••• .• .1110 • •The gage indicated t s the Twitting at the t taw h %ads were obs red on the tirig hall teea stir bog flume. The corresvond int?, discfnarge in second -f eet wais taken from a sear otrve bf;sed
cril
this table. This rnting flume is located in the same channel as the 6-fot trbd Lvrent meter gegings given.
iturtioee
Ourrent meter g.,.girtge. in Toting flume in seoond -feet with corresponding PO In feet.
dates indicated. These gagins8 nade on
-27-In order to rdake ni field comarison betueen the couuted discharge of a Parshall flurie and an ordinary ratin7 flume, there Vfaz; .u1].t a 6-foot flume in a ditch at 7 ock3r ?ord, Colorado as shown in figure 10. This flume wvs provided tAth sti1.lin v;ells for bot the 7a and Tjb gnges. ;11 index vas fixed near the to of each veil vIlich made it no sible to determine the heads to 0.01 foot by :cans of a depth uge. 7efe;ence points in te u - stre-:1 antd dovnstream wings of structure were used to determine the loss of head.
An ordinary rcCin flume, -flroviously constructed in the ditch at a point alout 100 yards.dmnstrean, wa calibrated by culrent Neter ::agin7,s and used t aseertuin
of the Parshall measArin flume. The condition of flocm throwt the ratinR flume was satisfactory. Table IT gives a
comparison between te computed discharge through this 6-foot flume, as compared uith the dischurge a shltin by the rating flume.
The 3-, 6- and 9-Inc Parshall Measurinr.7 Flume.
In the oriinaa investigation of this t::pe of measuring device, the 1-foot f11,,e was the spillest size tested, and becuse of the desirabilit• of usin this flume for snaller
lf.charges than coul:, be :/;:e - sre.1 1...aetic-.11 by use of the 1-fot; size,for both free and submerged flo- s,ealibrations were uwde on 3-, 6-, and 9-Inch fluue havin• different dimensions than those rhich governed in the larger sies. The general dimensions of these sriFt1 flu!.7ic-, are 7,iven in
0
-j
fp,
-Walls of suitable lenth installed in 'Field -I> 15-Y • -Walls of suitable length installed in . -\ 'NTABLE GAPAGITIliS OF TH76 PARSIL.IL LASURING iLUME, FOR THE 3-, 6-, and 9-INC1 OE5T LaGTHS. Letters refer to figure 1.7.
..••••••
A 2/3A
.Inoti9s It. in. It. in. .it. in. .it. in. .Ft. in. .it. in. it.
1/4 1 6 5/16 2
1/8 2
lo
3 .1 6 3/8 1 6 2 7/16 1 4 9 2 10 5/8 1 11 7 10 3/16 1 3 1/2 1 12
1/4 1 1 1/2 1.2 1 3 1/2 1 3 1/2 1 6 1 .,4 3 41/2 2 3 2.9 1 3 1 10 5/8 2 1 1 1/2. 3 4 1/2 2 3 5.7Free FlOw OODQuit7
K y Maximum Minimum
..._____---Ft. In. In. In. In. . See.-ft. .';.)9e.-ft.
0.03 ,05 .1
Yiguro 12...* Free flow discharge throltgh 644nch Psr31'7a11 tuesiarirr
num. A1,14 11-3611 rIonrta the downetree::1 wing$ Amy be at right arrlee
B ,
,
Ha WELL ,`,4' t PLAN F SECTION L-L •-•.•DIRECT ION OF FLOW
..-G
L
,
TASIA VI *--PLE2 YlOx 3-IWCH PABSAiLLL 51:4'%3URING 41-er Head H a based ou 4,-0.992 Ha 1.547 0.3C 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 .028 . 033 .037 .042 .047 . 053 .056 .064 . 070 . 076 ,.M:?_. 089 .095 . 102 . 10V . 117 .124 . 131 . 138 . 146 .170 . 17J . 187 .196 . 205 . -13 . . 231 . 241 . 250 ..460 . 269 . 279 . 28/ . 299 309 . 319 . 329 . 571 . 584 . 597 . 610 . 623 . 636 . 643 .662 . 675 . 689
.7o2
. 716 . 730 . 744 . 757 . 771 .786 . 800 . 814 . 828 .992 1.007 1.023 1.038 1.054 1.070 1.086 1.102 1. 118 1. 134TABU!: VI I FLO': rIROLIJP. 6- INJF NFAJURING ?LUKE. Basod on m.= 2. 06 ita1.68 Upper Head H a O. 00 IA') 0.02 0.0 0.04 0.06 0.06 O. 07 0.08 0.09
r aet zee. ft. .'ia 0. ft. Jcic. rt. ..;acs. ft. Jea. ft. Li, 1. ft. Selz,. ft. ititz. ft. Soo. f t. beo. ft.
0. Oa 0. 07 O. 08 0.09 0. 10 C. 11, ' 0. 12 0.15 . 2.0 . 16 . 30 . 31 . 32 . 34 . 36 . .36 . 49 . 41 . 43 . 4b . 47 . 40.-b0 . b6 . bd 6b . 67 69 . tiU . 32 . 8b . 60 . 92 . 94 . 97 . 99 1. : 1.34 1.07 1. 10 .80 1. 4b 1. qt8 i. b0 1. b.3 1. 66 1. b9 1. 62 1. 6b 1. 68 471 .90 1.74 1. 77 1. 61 1. 84 1. 87 1. 90 1. 93 1. 97 2. 00 1. :JO .S 2. 09 2. 12 2. 16 2. 19 2. 22 2. 26 1. 10 2.440 A. 43 2. 46 60 :,.. 64 1. 20 2. 7b Z. 76 2. 82 2. 46 2. d3 2.93 ,.. .97 3. 01 3.04 3. 08
7III I
TABLr, FLO i 9-1 L UI3?Lira.
1.53 Based on 4, = 3.07 /I• a Upper Head 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 as -
/set ,. ea. ft Sao. ft. Joe. ft. olo. ft. .-;so. ft. Jet). ft. ..)eo. ft. :Jo°. ft. ..;ea. ft. oez..*. ft.
0.10 0.09 0.10 0.12 0.14 .20 .26 .28 .30 .32 .30 .41 .51 .54 .56 .40 .76 .78 .81. .84 .50 1.06 1.10 1.13 1.16 .60 1.40 1.44 1.48 1.51 .70 1.78 1.82 1.86 1.90 .80 2.18 2.22 2.7 2.31 .0 2.61 2.66 2.70 2.75 1.00 3.07 3.12 3.17 3.21 1.10 3.55 3.60 3.65 3.70 1.20 4.06 4.11 4.16 4.22 1. 30 4. 59 4. 64 4. 69 4. 75 1.40 5.14 5.19 5.25 5.31 1.50 5.71 5.77 5.83 5.89 0.15 .35 .59 .87 1.20 1.tt., 1.94 2.3t' 2.79 3.26 3.75 4.27 4. SO 37 5.94 0.17 0.19 0.20 0.22 0.24 .37 .39 .41 .44 .46 .62 ,6.e .6? .70 .73 .90 .34 .97 1.00 1.03 1.23 1.26 1.30 1.33 1.37 1.59 1.63 1.66 1.70 1.74 1.98 2.02 4. 06 2.10 2.14 2.39 2.44 2.48 Z.. 5 2.57 2.84 2.98 2.93 4. 98 3.02 3.31 3.36 3.40 1.1,5 3.50 3.80 3.8b 3.30 3.95 01 4.32 4.$7 4.43 4.48 4. 53 4. .:k; 4.92 4.- ;37 5.085.03 42 5.48 5.5 5.59 5.65 6.00 6.06 6.12 6.16 6.24
